An endoscope is a tube equipped with lamplight, so that it may enter the stomach through the oral cavity or enter the body through other natural orifices. Pathological changes which may not be displayed under X-ray may be examined by the endoscope. Therefore, the endoscope is very useful to doctors. For example, with an endoscope, doctors may observe ulcers or tumors inside the alimentary tract, hereby establishing the best therapeutic plans.
The existing injection syringes for use with various endoscopes usually have a slender insertion part capable of inserting into the endoscope channel and an operating part connected with a base end of the insertion part. The insertion part comprises a double-layer tube having an outer tube and an inner tube which may be inserted into the outer tube in a way that it may be fed into and retracted from the outer tube freely. The operating part enables the inner tube to be fed into or retracted from the outer tube. A front end of the inner tube is provided with a hollow syringe needle.
The existing injection syringes usually have a single injection function. When in use, the whole feeding or retracting of the needle needs to be completed by hands, and control by hands of the operators is required during the whole operation. Therefore, the existing injection syringes are laborious and inconvenient to operation.
In addition, for the existing injection syringes for use with an endoscope, the length of the needle tip extending out from a cannula may be determined just before an operation. Once determined, the length cannot be changed during the operation, resulting in that the existing injection syringes are difficult to adapt to different disease parts and the piercing depth of the needle tip cannot be adjusted according to the specific situation of the affected part.